The supremacy of the capital city's footballers was such that, for the first official match of Luxembourg's national team against France on 29 October 1911, the starting lineup was entirely composed of Racing, Sporting and Union players.
The domination of the capital city's football clubs drew to a close at the end of the 1920s with the emergence of teams from the south of the country, such as CS Fola Esch and Red Boys Differdange.
The decline of sporting success thus led to a phenomenon that was to have a profound impact on the footballing community in the commune, namely the propensity of clubs to engage in mergers.
Sporting, the club of the centre of Luxembourg City, had found a pitch on what is today the Winston Churchill Square in 1910 and had also signed off in glory by bringing home the 1919 Championship.
These two mergers would quickly be crowned by success: Union, whose team was full of Luxembourgish internationals, won its sixth title in 1927.
On their magical pitch in the middle of a residential area of Luxembourg City, in permanent contact with its inhabitants and, above all, the youth, Spora experienced a near-explosive success.
Over 25 editions the Luxembourgish crowd would be able to witness such illustrious teams as Austria Vienna with its wunderkind Mathias Sindelar, PSV Eindhoven, Slavia Prague, Young Fellows Zurich, Beerschot Antwerp, Lanerossi Vicenza and even the Brazilian AC Bangu.
These matches lasted up until the day Spora moved to a new pitch on the Route d'Arlon to a Stadium that is today home of the Luxembourgish national team, the Stade Josy Barthel.
Before completely disappearing from the peak of Luxembourgish football, they did manage to snag two cup wins in 1965 and 1966, under the auspices of their player-coach Vic Nurenberg.
Players such as Johny Léonard, three-time top goal scorer in the national league before joining FC Metz, and Nico Braun became emblematic of this period.
It was the first trophy of its existence, dating back to 1922, and it was celebrated at the Parc des Sports, nowadays called Stade Camille Polfer which serves as the training grounds for Racing FC Union.
Racing FC Union was thus born out of troubled times, the politics behind the scenes having destroyed a lot of the trust and support the clubs had had amongst the general population.
After extra-time, they clinched the win on penalties, with Julien Jahier scoring the winner in his last match for the club.